Rheostat



H. L. ZABRISKIE. HHEOSTAT. APPLICATION FILED IuLY 20.192I.

IIIIIIIIIIIIIIIII;

WITNE SES? INVENITOl `*c" l Bj Patented Dec. 5, 1922.

Patented Dec. 5, 1922.

UNITED STATES PATENT OFFICE..

HENRY L. ZABRISXIE, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO DIEHL MANUFAC- TURING COMPANY. OF ELIZABETH, NEW JERSEY, A 'CORPORATION OF NEW JERSEY.

RHEOSTAT.

Application tiled July 20,

To all yw hom t may conector .j

Be it known that I, HnNRY L. Zanlsnni, a citizen of the United States, residing at lllestield, in the county of `Union and Statey of New Jersey, have invented certain new and useful Improvements in Rheostats, of. which the `following is a specification, reference being had therein to the accompanying drawings.y

This invention relates to electrical resistance units or rheostats, more particularly of the type represented in the U. S. patent to 15mm, No. 1,369,407, of February 22, 1921, and has for an object to simplify and improve thc rheostat contact arm and the means for mounting it.

Resistance units of the typereferred to usually comprise a support of some heatresisting insulating material, such as porcelain, upon which is wound a length of resistance wire tapped at intervals to a series of contact points over which plays the free end of a resilient contactarm pivoted at its other end to the support. Such a resistance unit is adapted for mounting in a suitable casing carrying an operating arm which transmits motion to the contact arm. In order that thecontact arm may be stiff or heavy enough to afford a substantial connection with the operating arm and yet bear resiliently upon the contact points, it hashereton Yfore been the practice to make such contactarmv in two sections, one ofwhich is stiff or non-resilient andl the other resilient. The non-resilient section is pivoted to t-he support to swing only in a plane at right angles to the axis of the pivot, and the resilient section is fixed at one end to the sti" section `and in effect forms a resilient extension of theV latter. Provision is made for connecting the operating arm with the non-resilient section `ot the contact arm. Thisconstruction necessitates the making andassembling of severaly small parts to provide the pluralsectioned arm.

According to the present improvement, the arm is made of one piece of comparatively stiff or non-resilient stock; the requisite yielding pressure of such arm upon the contact points being provided for by forming the arm with an aperture somewhat larger than the pivot post and by interposing a.- spring between such arm and ahead on the pivot post; the pivoted end of the arm being preferably' formed with a down-turned lip 1921. serial No. 456,111. I

affording a contact segment adapted to bear yieldingly upon a terminal element at the base of the pivot post. i

In the accompanying drawings illustrating the preferred embodiment yof the invention, Fig. l is a top plan view of the resistance unit. Fig. 2 is a bottom plan view or the same. Fig. 3 is a longitudinal vertical section on the line 3-3, Fig. 1. Fig. 4 is a fragmentary bottom plan view of the. contact-arm and Fig. 5 is a fragmentaryy leftend elevation of the resistance unit.

In the specific embodiment of the inveniion illustrated. 1 indicates a support of suitable insulating material, such as porcelain, which is provided with openings 2 for screws or bolts whereby it may be mounted in any desiredr place. A series of the. usual. contact points 3 are mounted at one end of the support while at the other end is mounted a pivot post. The pivot'post is preferably formed with an enlarged head 5, a cylindrical body 6, and a reduced cylindrical shank 7 affording a shoulder 8 at the 'uncture of the body 6 and shank 7 The s ank 7 enters a suitable aperture in the support 1 and is threaded to receive the holding screw 9 which passes through the terminal plate 1() and secures the latter firmly in electrical contact relation with the pivot post. Inter.- posed between the shoulder 8 and the support 1 is a. contact element in the form of a washer 11 which is also firmly held inelectrical contact with the pivot post by the inwidth and troughed slightly in order that it may readily play over the contact points without catching on the latter. At its opposite end the arm 12 is formed with an aperture 14 slightly larger than the post 6 'and preferably having rounded walls so as to freely embrace the post 6 and permit a limited tilting movement of the free and of the arm toward and away from the plane of the contacts 3.. Preferably, the rearward extremity of the arm 12 is formed with a down-turned toel forming a Contact segment adapted to bear upon the Contact element or washer ll; the opposite ends of the arm i2 being yieldingly held in contact with one of the contact points 3 and the contact element ll, respectively, by means of the spring lr6v surrounding the body 6 of the pivot post and interposed between the head 5 of such post and the body of the contact arm. A Washer 17 may be interposed between the spring 16 and arm l2 although it is not essential.

Thesupport l is wound as usual, with a resistor or length of resis anco wire i8 tapped at intervals to the contacts 8 and connected at one end to the terminal plate lll.

It will be observed that in the construction described, the arm l2 is at all times held in yielding electrical Contact with the contact element ll'and that the tree end oit the arm bears yieldingly uponthe contact oints, although the arm itself is made in one piece and is relatively stiff and unyielding. The segmental Contact surface 2O ez;- tending circularly about the post in a plane at right angles to the axis of such post, atto-rds an ellicient contact surface of reduced area` permitting free Aturning of the arm l2 about the pivot post and serving to inaintainthe arm in a plane parallel to the plane of the contact points and to steady the arm l2 against tilting on its longitudinal axis.

Having thus set forth the nature ofthe invention, what l 4claim herein ish l. A rheostat comprising a support, a plurality of resistor connected vcontact points and a pivot post lixedly mounted on said support,'a Contact arm having` near one end an laperture freely embracing said post and per'nrtting limited tilting movement ot said arm transversely ofthe plane oll the contact points, and a spring mounted on said Apost, and serving to press said arm yieldingly upon said contact points.

2. rheostat comprising a support, a plurality ont' resistor connected contact points and a pivot post xedly mounted on said support, a contact element-at the base of the pivot"post, a contact arm having near one enden4 aperture. freely embracing said post and permitting limited tilting movement of said arm transversely ofthe plane of the Contact points, and a. spring mounted on said post and serving to press said arm upon said Contact points and `contact element.

3. il rheostat comprising a support, a plurality ol resistor connected contact points and a pivot post Xe-dly mounted on said support, a Contact element at the base of the pivot post, a contact arm freely embracing said pivot post and having` adown-turned toe adapted to bear upon said Contact element, vand a spring` mounted on said post and serving to hold the contact arm yieldingly in electrical Contact with said contact elenient and a contact point. y

d. 'Ar rheostat' comprising a support, a plurality oli' resistor connected Contact points on said support, a pivot post on said support, contact element at the base el said pivot post, a Contact arm element apertured to freely embrace said post, one ot said elements being formed with a Contact segment adapted to bear upon `the other element, and a spring` tor yieldingly holding said arm in engagement with said Contact element and any one or the cont-act. points to which it may he turned. l-

5. Il rheostat comprising ay support, a pivot post mounted ron said support and formed at its upper end with an enlarged head, ar contact element on saidsupport at the base otsaidpost, a contact arm apertured to freely embrace said post between said head and contact element, said arm being' formed adjacent said aperture w'zth a Contact segment adapted to bear uponl said Contact element, spring surrounding said post between said head and contact arm, and a plurality of resistor connected contact points mounted on said support within range ot said arm. f

6. A; rheostat com'lzirising a support, aplurality ofresistor-connected contact points and a Contact elementvearried by saidsupport, a contact arm 'freely pivoted interniediate its endson said support and havingr a limited tilting increment transversely ot the plane oic thecontact points, anda spring acting'on said arm between the ends oi said arnrto hold it yieldingly in contact with said Contact element andl contact points.

ln testimony7 whereof,4 I have signed my name lto this specification."

HENRY L, ZABRISISIE. 

